"This is a hypothetical question. We can't just answer this question as of now. We can just say that we will deal with this (Coalgate scam investigation) in a professional manner. This is an investigation and as and when the matter comes up, it will be answered," Additional Director of CBI Rupak Kumar Dutta said when asked whether the Prime Minister would be interrogated in connection with the Coalgate scam.

Asked about the alleged missing files in the Coal Ministry, Dutta, who was in the city to attend a programme, said "CBI has asked for some documents (regarding the investigation).

"The Coal Ministry is looking for those documents. They have not said that they will not give those files. When they get those files they will give it to us," he said. On Wednesday, CBI Director Ranjit Sinha had also evaded the question of examining Prime Minister Manmohan Singh in connection with its probe in the coal blocks allocation scam.

His comments were sought in the wake of a report that the investigation team in the coal allocation scam has suggested questioning the PM, which the CBI Director has put on hold.

CBI has so far registered 13 FIRs in connection with the coal blocks allocation scam.